Implantable physiological sensors are used for monitoring patient conditions and for managing or controlling therapies delivered to a patient. For example, there are numerous reasons that a clinician is interested in monitoring the hemodynamic status of a patient. Various implantable sensors such as blood pressure sensors, oxygen sensors, impedance sensors, acoustical sensors or the like have been proposed or used to monitor physiological signals in the body to obtain surrogate measures for cardiac output or other clinical hemodynamic parameters. Reliable, ambulatory monitoring of a hemodynamic parameter can be useful in controlling numerous types of device delivered therapies, such as cardiac resynchronization therapy (CRT) used to treat heart failure or cardioversion defibrillation shocks used to treat hemodynamically unstable arrhythmias. A need remains for miniaturized physiological sensors that have low power requirements and provide reliable sensing of signals that can be used to monitor the hemodynamic status of a patient.